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  <div class="section" id="macro">
<span id="command:macro"></span><h1>macro<a class="headerlink" href="#macro" title="Permalink to this headline">¶</a></h1>
<p>Start recording a macro for later invocation as a command</p>
<div class="highlight-cmake notranslate"><div class="highlight"><pre><span></span><span class="nf">macro(</span><span class="nv">&lt;name&gt;</span><span class="w"> </span><span class="p">[</span><span class="nv">&lt;arg1&gt;</span><span class="w"> </span><span class="p">...]</span><span class="nf">)</span><span class="w"></span>
<span class="w">  </span><span class="nv">&lt;commands&gt;</span><span class="w"></span>
<span class="nf">endmacro()</span><span class="w"></span>
</pre></div>
</div>
<p>Defines a macro named <code class="docutils literal notranslate"><span class="pre">&lt;name&gt;</span></code> that takes arguments named
<code class="docutils literal notranslate"><span class="pre">&lt;arg1&gt;</span></code>, … Commands listed after macro, but before the
matching <span class="target" id="index-0-command:endmacro"></span><a class="reference internal" href="endmacro.html#command:endmacro" title="endmacro"><code class="xref cmake cmake-command docutils literal notranslate"><span class="pre">endmacro()</span></code></a>, are not executed until the macro
is invoked.</p>
<p>Per legacy, the <span class="target" id="index-1-command:endmacro"></span><a class="reference internal" href="endmacro.html#command:endmacro" title="endmacro"><code class="xref cmake cmake-command docutils literal notranslate"><span class="pre">endmacro()</span></code></a> command admits an optional
<code class="docutils literal notranslate"><span class="pre">&lt;name&gt;</span></code> argument. If used, it must be a verbatim repeat of the
argument of the opening <code class="docutils literal notranslate"><span class="pre">macro</span></code> command.</p>
<p>See the <span class="target" id="index-0-command:cmake_policy"></span><a class="reference internal" href="cmake_policy.html#command:cmake_policy" title="cmake_policy"><code class="xref cmake cmake-command docutils literal notranslate"><span class="pre">cmake_policy()</span></code></a> command documentation for the behavior
of policies inside macros.</p>
<p>See the <a class="reference internal" href="#macro-vs-function"><span class="std std-ref">Macro vs Function</span></a> section below for differences
between CMake macros and <span class="target" id="index-0-command:function"></span><a class="reference internal" href="function.html#command:function" title="function"><code class="xref cmake cmake-command docutils literal notranslate"><span class="pre">functions</span></code></a>.</p>
<div class="section" id="invocation">
<h2>Invocation<a class="headerlink" href="#invocation" title="Permalink to this headline">¶</a></h2>
<p>The macro invocation is case-insensitive. A macro defined as</p>
<div class="highlight-cmake notranslate"><div class="highlight"><pre><span></span><span class="nf">macro(</span><span class="nb">foo</span><span class="nf">)</span><span class="w"></span>
<span class="w">  </span><span class="nv">&lt;commands&gt;</span><span class="w"></span>
<span class="nf">endmacro()</span><span class="w"></span>
</pre></div>
</div>
<p>can be invoked through any of</p>
<div class="highlight-cmake notranslate"><div class="highlight"><pre><span></span><span class="nf">foo()</span><span class="w"></span>
<span class="nf">Foo()</span><span class="w"></span>
<span class="nf">FOO()</span><span class="w"></span>
</pre></div>
</div>
<p>and so on. However, it is strongly recommended to stay with the
case chosen in the macro definition.  Typically macros use
all-lowercase names.</p>
</div>
<div class="section" id="arguments">
<h2>Arguments<a class="headerlink" href="#arguments" title="Permalink to this headline">¶</a></h2>
<p>When a macro is invoked, the commands recorded in the macro are
first modified by replacing formal parameters (<code class="docutils literal notranslate"><span class="pre">${arg1}</span></code>, …)
with the arguments passed, and then invoked as normal commands.</p>
<p>In addition to referencing the formal parameters you can reference the
values <code class="docutils literal notranslate"><span class="pre">${ARGC}</span></code> which will be set to the number of arguments passed
into the function as well as <code class="docutils literal notranslate"><span class="pre">${ARGV0}</span></code>, <code class="docutils literal notranslate"><span class="pre">${ARGV1}</span></code>, <code class="docutils literal notranslate"><span class="pre">${ARGV2}</span></code>,
…  which will have the actual values of the arguments passed in.
This facilitates creating macros with optional arguments.</p>
<p>Furthermore, <code class="docutils literal notranslate"><span class="pre">${ARGV}</span></code> holds the list of all arguments given to the
macro and <code class="docutils literal notranslate"><span class="pre">${ARGN}</span></code> holds the list of arguments past the last expected
argument.
Referencing to <code class="docutils literal notranslate"><span class="pre">${ARGV#}</span></code> arguments beyond <code class="docutils literal notranslate"><span class="pre">${ARGC}</span></code> have undefined
behavior. Checking that <code class="docutils literal notranslate"><span class="pre">${ARGC}</span></code> is greater than <code class="docutils literal notranslate"><span class="pre">#</span></code> is the only
way to ensure that <code class="docutils literal notranslate"><span class="pre">${ARGV#}</span></code> was passed to the function as an extra
argument.</p>
</div>
<div class="section" id="macro-vs-function">
<span id="id1"></span><h2>Macro vs Function<a class="headerlink" href="#macro-vs-function" title="Permalink to this headline">¶</a></h2>
<p>The <code class="docutils literal notranslate"><span class="pre">macro</span></code> command is very similar to the <span class="target" id="index-1-command:function"></span><a class="reference internal" href="function.html#command:function" title="function"><code class="xref cmake cmake-command docutils literal notranslate"><span class="pre">function()</span></code></a> command.
Nonetheless, there are a few important differences.</p>
<p>In a function, <code class="docutils literal notranslate"><span class="pre">ARGN</span></code>, <code class="docutils literal notranslate"><span class="pre">ARGC</span></code>, <code class="docutils literal notranslate"><span class="pre">ARGV</span></code> and <code class="docutils literal notranslate"><span class="pre">ARGV0</span></code>, <code class="docutils literal notranslate"><span class="pre">ARGV1</span></code>, …
are true variables in the usual CMake sense.  In a macro, they are not,
they are string replacements much like the C preprocessor would do
with a macro.  This has a number of consequences, as explained in
the <a class="reference internal" href="#argument-caveats"><span class="std std-ref">Argument Caveats</span></a> section below.</p>
<p>Another difference between macros and functions is the control flow.
A function is executed by transferring control from the calling
statement to the function body.  A macro is executed as if the macro
body were pasted in place of the calling statement.  This has the
consequence that a <span class="target" id="index-0-command:return"></span><a class="reference internal" href="return.html#command:return" title="return"><code class="xref cmake cmake-command docutils literal notranslate"><span class="pre">return()</span></code></a> in a macro body does not
just terminate execution of the macro; rather, control is returned
from the scope of the macro call.  To avoid confusion, it is recommended
to avoid <span class="target" id="index-1-command:return"></span><a class="reference internal" href="return.html#command:return" title="return"><code class="xref cmake cmake-command docutils literal notranslate"><span class="pre">return()</span></code></a> in macros altogether.</p>
</div>
<div class="section" id="argument-caveats">
<span id="id2"></span><h2>Argument Caveats<a class="headerlink" href="#argument-caveats" title="Permalink to this headline">¶</a></h2>
<p>Since <code class="docutils literal notranslate"><span class="pre">ARGN</span></code>, <code class="docutils literal notranslate"><span class="pre">ARGC</span></code>, <code class="docutils literal notranslate"><span class="pre">ARGV</span></code>, <code class="docutils literal notranslate"><span class="pre">ARGV0</span></code> etc. are not variables,
you will NOT be able to use commands like</p>
<div class="highlight-cmake notranslate"><div class="highlight"><pre><span></span><span class="nf">if(</span><span class="no">ARGV1</span><span class="nf">)</span><span class="w"> </span><span class="c"># ARGV1 is not a variable</span>
<span class="nf">if(</span><span class="no">DEFINED</span><span class="w"> </span><span class="no">ARGV2</span><span class="nf">)</span><span class="w"> </span><span class="c"># ARGV2 is not a variable</span>
<span class="nf">if(</span><span class="no">ARGC</span><span class="w"> </span><span class="no">GREATER</span><span class="w"> </span><span class="m">2</span><span class="nf">)</span><span class="w"> </span><span class="c"># ARGC is not a variable</span>
<span class="nf">foreach(</span><span class="nb">loop_var</span><span class="w"> </span><span class="no">IN</span><span class="w"> </span><span class="no">LISTS</span><span class="w"> </span><span class="no">ARGN</span><span class="nf">)</span><span class="w"> </span><span class="c"># ARGN is not a variable</span>
</pre></div>
</div>
<p>In the first case, you can use <code class="docutils literal notranslate"><span class="pre">if(${ARGV1})</span></code>.  In the second and
third case, the proper way to check if an optional variable was
passed to the macro is to use <code class="docutils literal notranslate"><span class="pre">if(${ARGC}</span> <span class="pre">GREATER</span> <span class="pre">2)</span></code>.  In the
last case, you can use <code class="docutils literal notranslate"><span class="pre">foreach(loop_var</span> <span class="pre">${ARGN})</span></code> but this will
skip empty arguments.  If you need to include them, you can use</p>
<div class="highlight-cmake notranslate"><div class="highlight"><pre><span></span><span class="nf">set(</span><span class="nb">list_var</span><span class="w"> </span><span class="s">&quot;${ARGN}&quot;</span><span class="nf">)</span><span class="w"></span>
<span class="nf">foreach(</span><span class="nb">loop_var</span><span class="w"> </span><span class="no">IN</span><span class="w"> </span><span class="no">LISTS</span><span class="w"> </span><span class="nb">list_var</span><span class="nf">)</span><span class="w"></span>
</pre></div>
</div>
<p>Note that if you have a variable with the same name in the scope from
which the macro is called, using unreferenced names will use the
existing variable instead of the arguments. For example:</p>
<div class="highlight-cmake notranslate"><div class="highlight"><pre><span></span><span class="nf">macro(</span><span class="nb">bar</span><span class="nf">)</span><span class="w"></span>
<span class="w">  </span><span class="nf">foreach(</span><span class="nb">arg</span><span class="w"> </span><span class="no">IN</span><span class="w"> </span><span class="no">LISTS</span><span class="w"> </span><span class="no">ARGN</span><span class="nf">)</span><span class="w"></span>
<span class="w">    </span><span class="nv">&lt;commands&gt;</span><span class="w"></span>
<span class="w">  </span><span class="nf">endforeach()</span><span class="w"></span>
<span class="nf">endmacro()</span><span class="w"></span>

<span class="nf">function(</span><span class="nb">foo</span><span class="nf">)</span><span class="w"></span>
<span class="w">  </span><span class="nf">bar(</span><span class="nb">x</span><span class="w"> </span><span class="nb">y</span><span class="w"> </span><span class="nb">z</span><span class="nf">)</span><span class="w"></span>
<span class="nf">endfunction()</span><span class="w"></span>

<span class="nf">foo(</span><span class="nb">a</span><span class="w"> </span><span class="nb">b</span><span class="w"> </span><span class="nb">c</span><span class="nf">)</span><span class="w"></span>
</pre></div>
</div>
<p>Will loop over <code class="docutils literal notranslate"><span class="pre">a;b;c</span></code> and not over <code class="docutils literal notranslate"><span class="pre">x;y;z</span></code> as one might have expected.
If you want true CMake variables and/or better CMake scope control you
should look at the function command.</p>
</div>
</div>


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  <h3><a href="../index.html">Table of Contents</a></h3>
  <ul>
<li><a class="reference internal" href="#">macro</a><ul>
<li><a class="reference internal" href="#invocation">Invocation</a></li>
<li><a class="reference internal" href="#arguments">Arguments</a></li>
<li><a class="reference internal" href="#macro-vs-function">Macro vs Function</a></li>
<li><a class="reference internal" href="#argument-caveats">Argument Caveats</a></li>
</ul>
</li>
</ul>

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